1. Field of the Invention
This invention relates to a control for a manually shifted compound transmission of the splitter type and more particularly to a control for compound splitter type transmission having a main section, preferably with an even number of forward speed ratios and a single reverse speed ratio, a splitter type auxiliary section and a selectively engagable and disengagable extended range section for providing increased ratio coverage in the low speed ratios.
The control utilizes the unused leg of a standard H-type shift pattern to cause the extended range section to be engaged to provide an additional gear reduction in the low speed ratio of the main transmission section and, except for one main section clutch, is utilized with the same, or substantially the same, main and auxiliary transmission section components as a standard (non-extended range) compound splitter type transmission. Also, the control maintains the standard progressive movement of the lever on the entire H-type shift pattern.
2. Description of the Prior Art
Compound change gear transmissions comprising a multiple speed main transmission section connected in series with one or more multiple speed auxiliary transmission sections are well known in the prior art. Such transmissions are usually utilized with heavy duty vehicles and are of the splitter type or the range type or a combination thereof, as may be seen by reference to U.S. Pat. Nos. 3,105,395; 3,648,546; 3,799,002; 3,921,469; 3,924,484; 2,932,988 and 3,229,551, the disclosures of which are all hereby incorporated by reference.
The control of the present invention is particularly well suited for use in connection with a compound splitter type change gear transmission of the semi-blocked type as disclosed in European Pat. No. 0071353, the disclosure of which is hereby incorporated by reference. Briefly, such a semi-blocked transmission is sold by the Assignee of this invention, Eaton Corporation, and its British subsidiary, Eaton Limited, under the trademark "Twin-Splitter" and comprises a multiple speed main transmission section connected in series with a blocked splitter type auxiliary transmission section.
While semi-blocked splitter type compound change gear transmissions are very well received, there has been, for certain applications, a need for extended low speed ratio coverage and/or for structure allowing the use of an auxiliary section countershaft PTO (i.e. "power take off" device). These drawbacks of the prior art are overcome or minimized by the provision of an extended range section which is utilized with an otherwise substantially standard semi-blocked splitter type compound transmission and provides extended low speed ratio coverage for the transmission and/or allows the transmission output shaft to be selectively, drivingly disconnected from the auxiliary transmission section countershaft thereby allowing the use of an auxiliary countershaft driven PTO.
The above is accomplished in an otherwise substantially standard semi-blocked splitter type compound transmission by rotationally fixing the auxiliary section output gear to a sleeve shaft which sleeve shaft is independently rotatable of both the transmission mainshaft and the transmission output shaft. An extended range section countershaft gear is rotatable driven by the auxiliary section countershaft and is constantly meshed with an extended range section output shaft gear which surrounds but is independently rotatable relative to the transmission output shaft. An extended range section clutch means is provided having three selectable positions. In the first position, the range section clutch will drivingly connect the sleeve shaft to the output shaft to provide standard splitter type auxiliary transmission section operation. In the second position of the range section clutch, the clutch permits independent rotation between the sleeve shaft, the output shaft and the range section output shaft gear whereby the auxiliary section countershaft(s) can be driven independently of the output shaft for auxiliary section countershaft PTO purposes. In the third position of the range section clutch, preferably only permitted in the low gear ratio position of the main transmission section, the range section output shaft gear is rotationally fixed to the output shaft and the sleeve shaft is rotatably independent of the output shaft providing a multiple deep reduction range depending upon the engaged one of the splitter section mainshaft gears.
While such an extended range splitter type transmission is highly advantageous, the requirement for operation of a separate extended range selector switch in addition to operation of the auxiliary section selector and the shift lever could complicate manual operation of such transmissions.
Controls responsive to shift lever position for shifting the auxiliary sections of range type transmissions and/or two-speed axles connected in series with simple transmissions are known in the prior art as may be seen by reference to U.S. Pat. Nos. 4,455,883 and 4,275,612, the disclosures of which are incorporated by reference. These controls were not suited for control of splitter type compound transmissions in general nor for control of an extended range section connected in series with a splitter type auxiliary transmission in particular, did not without extensive modification retain the H-type shift pattern progression and/or tended to require complicated and/or expensive modifications to the shift tower/shift bar housing assemblies.